The strike occurred in the province's Chakh district, according to the Afghan spokesman, Gen. Zahir Azimi, who said eight Afghan National Army troops were also wounded in the incident.

Azimi said an investigation was underway and that "the defense minister and all the staff of the defense ministry were saddened by the incident."

A spokeswoman for the international forces in Afghanistan, Maj. Cathleen Snow, told The Associated Press in an email that five Afghan soldiers were accidentally killed in an operation in the country's east. She did not specify whether aircraft were involved and whether the deaths were the result of an airstrike.

"We can confirm that at least five Afghan National Army personnel were accidentally killed this morning during an operation in eastern Afghanistan," said Snow. "An investigation is being conducted at this time to determine the circumstances that led to this unfortunate incident. Our condolences go out to the families of the ANA soldiers who lost their lives and were wounded."

Earlier, a provincial government official said that 17 soldiers were wounded in the airstrike. The discrepancy in the number of wounded could not immediately be reconciled. The Logar official spoke on condition of anonymity because he was not authorized to talk to the media.

Later in Logar, provincial officials were meetings to decide their response and to conduct a further investigation into the incident.

The airstrike is likely to draw another verbal attack from President Hamid Karzai against U.S. and NATO soldiers in his country.

Karzai has been deeply critical of civilian deaths by international forces and his relationship with Washington has been on a downward spiral for several years. But in the last year, Karzai's language has been much more harsh. He has accused the international troops of being occupiers, colluding with the Taliban insurgents and carelessly killing Afghan civilians.

The testy relationship has kept Karzai from signing a security agreement with the United States that would allow for a residual force of U.S. and NATO troops to stay behind in Afghanistan after the end of December, when all international forces are to leave the country in an ending to the 13 years of war.

Karzai has cited civilian casualties as one of his reasons for refusing to sign the deal. He has sought guarantees from the United States to protect Afghan citizens.

"We value the strong relationship with our Afghan partners, and we will determine what actions will be taken to ensure incidents like this do not happen again," said the NATO spokeswoman, Snow, in her email to the AP.

Previously, Karzai had ordered an end to all coalition air strikes unless they were first cleared by the defense ministry.

There were no available details about Thursday's airstrike and what procedure was involved before it was carried out.